Fixed and mobile communication systems are converging. Packet-based networks such as an Internet Protocol (IP) network now have the ability to packetize and transmit the data content of telephony communication. This configuration is known as a Voice over IP (VoIP) network, and can support voice, video, and/or data content. A variety of global standardization bodies have been created to set the standards for this convergence. For instance, the Alliance for Telecommunications Industry Solutions (ATIS) is a U.S.-based body that promotes technical and operations standards for the telecommunications and related information technologies industry worldwide. In addition, the Telecoms and Internet Converged Services and Protocols for Advanced Networks (TISPAN) group is a standardization body of the European Telecommunication Standard Institute (ETSI) specializing in fixed networks and Internet convergence. The network concept developed by ETSI TISPAN is commonly referred to as Next Generation Network (NGN). It leverages portions of the Internet Protocol Multimedia Subsystem (IMS) architecture as specified by the Third Generation Partnership Project (3GPP). The architecture of these systems typically provides users with services, such as security, charging, delivery of content data to the user devices by service providers, and/or session management to support the various services within that system.